(a) Technical Field
The present invention relates to a system and method for controlling clutch engagement in a hybrid vehicle, which can improve acceleration performance and driving performance, reducing engagement impact, and providing various clutch engagement modes in a simple and convenient manner.
(b) Background Art
A hybrid vehicle, in the broad sense, means a vehicle driven by at least two different types of power source combined. However, generally, it refers to a vehicle powered by an engine that runs on fuel and a motor that runs on an electric battery. Such a hybrid vehicle is referred to as a hybrid electric vehicle.
To meet the demands of today's society for the improvement of fuel efficiency and the development of a more environmentally friendly product, research and development is being actively conducted on hybrid electric vehicles.
As known in the art, hybrid electric vehicles have various power transfer structures. Most hybrid electric vehicles that have been researched up to present adopt a parallel type structure or a serial type.
Here, the serial type in which the engine and the motor are arranged in series has the advantages of a simpler structure and simpler control logic than the parallel type. However, since it stores mechanical energy from the engine in a battery used to power the motor and drive the vehicle, it has the disadvantage of poor efficiency in converting energy.
In contrast, the parallel type has the disadvantages of a more complicated structure and more complicated control logic than the serial type. However, since it can use the engine's mechanical energy and the battery's electrical energy simultaneously, it has the advantage of efficiency in using energy.
Meanwhile, as shown in FIG. 1, a typical hybrid vehicle includes an integrated starter and generator (ISG) 101, an engine 103, a clutch 105, a motor 107, and a transmission 109, in which the positions of the IGS 101 and the engine 103 may be shifted.
The ISG 101 is directed to a motor capable of motoring and generating. It is connected to the engine 103 by mechanical means such as a belt, a chain, a gear, etc., and its connection ratio is determined variously as occasion demands. The motor 107 is directed to a motor capable of motoring and generating. The transmission 109 is a device capable of varying the gear ratio between the input and output through an automatic control and composed of one or more planet gear set or differential gear set.
Meanwhile, in a hybrid electric vehicle having the main clutch 105 controlled automatically or a vehicle equipped with an automated manual transmission (AMT), the driving performance and durability of the vehicle depends on the engagement mode of the main clutch which acts to interrupt or transmit the engine power.
However, conventionally, an appropriate clutch engagement mode is not selected based on various factors, and a change in torque caused in the clutch engagement is not actively controlled, and thus the durability, driving performance, acceleration performance and fuel efficiency of the vehicle are deteriorated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.